We argue that \(\tau _{\text{iso}}\)  should be preferred
to \(\tau _{\text{gyro}}\)  for WASP-77 A. We assume that
WASP-77 B has the same metallicity and extinction we
inferred for WASP-77 A and use the same procedure described
above to fit the MIST isochrone grid to Sloan Digital Sky Survey
[1]}, [2]}, [3]}, [4]}, [5]}, [6]}
\(u\)  and Gaia DR2 \(G\)  photometry as well as a Gaia EDR3 parallax for
WASP-77 B. We find consistent ages for WASP-77 A \(\tau _{\text{iso}}\) 
= \(7.99^{+1.90}_{-1.71}\)  and WASP-77 B \(\tau _{\text{iso}}\) 
= \(7.3^{+4.4}_{-4.6}\) . We also note that [7]} studied
the X-ray properties of the WASP-77 system and found X-ray-based ages
consistent with our isochrone-based age inferences for both stars.
As we will show in Section , the difference between the
isochrone- and gyrochronology-based age inferences results from tidally
mediated angular momentum exchange between the WASP-77 A system's orbital
angular momentum and the rotational angular momentum of WASP-77 A.
